Continuous card form

ABSTRACT

Improved folding during manufacture of continuous forms and refolding during runs through a high-speed printer are obtained by a fold score comprising a series of perforations extending across the detachable marginal strips and transversely aligned with, and preferably the same size as, the groups of perforations constituting the ties between the break-out cards and intervening medial strips. Especially in a two-card wide form, the structural strength of each medial strip adjacent a fold score line is suitably reduced, such as by a slot, to prevent toggle-like stiffening at the fold line, and consequent stacking jams, such as can occur during refolding of the form upon sudden stops following a high-speed line skip in a printer. In grain long forms, the overlapping plies providing the medial strip are heat sealed only at selected areas rather than along the entire strip to reduce medial strip shrinkage and further improve ease of stacking.

atet 91 Johnson et a1.

[ CONTINUOUS CARD FORM [75] Inventors: Oliver D. Johnson, E. Brunswick;

Kenneth B. Maynard, Belle Mead, both of NJ.

[73] Assignee: International Business Machines Corporation, Armonk, NY.

[22] Filed: Feb. 16, 1971 [21] Appl. No.: 115,448

[52] US. Cl 281/5, 270/6 F [51] Int. Cl 342d 19/00 [58] Field ofSearch..... 2231/5; 2232/3 B, 12 R, 12 A,

[56] References Cited UNITED STATES PATENTS 2,700,556 l/l955 Holmwood281/5 2,627,427 2/1953 -Weimont 281/5 3,450,419 6/1969 Eichorn 28l/53,114,565 12/1963 Sornberger 281/5 FOREIGN PATENTS OR APPLICATIONSGermany 282/1 1.5 A

[111 3,809,1 [4 1 May 7,1974

Primary Examiner-1erome Schnall Attorney, Agent, or Firm-Henry E. Otto,Jr.

[57] ABSTRACT Improved folding during manufacture of continuous formsand refolding during runs through a high-speed printer are obtained by afold score comprising a series of perforations extending across thedetachable marginal strips and transversely aligned with, and preferablythe same size as, the groups of perforations constituting the tiesbetween the break-out cards and intervening medial strips. Especially ina two-card wide form, the structural strength of each medial stripadjacent a fold score line is suitably reduced, such as by a slot, toprevent toggle-like stiffening at the fold 9 line, and consequentstacking jams, such as can occur during refolding of the form uponsudden stops following a high-speed line skip in a printer. In grainlong forms, the overlapping plies providing the medial strip are heatsealed only at selected areas rather than along the entire strip toreduce medial strip shrinkage and further improve ease of stacking.

10 Claims, 17 Drawing Figures PATENTEDMY 7 1914 SHEEI 1 BF 5 A TTORNE YThis invention relates to continuous form stationery, and moreparticularly to a continuous form comprising a series of break-outtabulating cards with means providing initial folding with equalfacility in either direction and refolding in the same direction withoutstiffening or kinking during runs through a highspeed printer or thelike.

BACKGROUND OF THE INVENTION For many years. continuous card forms havebeen made according to the teachings of U. S. Pat. No. 2,700,556,assigned to the assignee of the present invention. In these forms, thefold score in the side marginal strips consists of a line of short cutsextending transversely in alignment with a line of slits that constitutethe long edges of the break-out card. These slits extend between groupsof transversely aligned perforations; i.e., each group generallyconsists of four perforations, and the slits extend tangentially to saidperforations and cut tangentially into the outermost perforations ineach group. These perforations are intentionally offset from the slitsand recessed within the card edges so that the small tufts of paperfiber that remain when the ties are broken will not impair processing ofthe cards through data processing equipment.

With this arrangement, the form does not fold along a straight line. Theform tries to fold along a line coincident with the center line of theperforations until it reaches the marginal strips; then it shiftsslightly to a line coincident with that of the short cuts. This is notas aesthetically pleasing and precise as having a truly straight foldline. The short cuts are cut along the same line as the slits so theycan be formed in the same operation. To shift the line of short cutsslightly into alignment with the center line of the perforations in anattempt to provide a truly straight fold line would require either amore expensive too] or an additional sequential cutting operation. But,most important, since the short cuts are made with beveled cuttingblades, forms cannot be folded in either direction with equal facilityalongjust any score line. To facilitate folding with minimal effort,short cuts have to be made alternately from the back and front of theform; if the score is made repeatedly from the same side, the bevel ofthe cutting blade will aid folding in one direction and hinder foldingin the opposite direction. It follows, then, that with fold scoresconsisting of short cuts, folded stacks must have an odd number, e.g.,three, cards between each fold, when the score is made from alternatesides to avoid folding difficulties.

Attempts to increase productivity by increasing folding speed duringmanufacture of continuous card forms, and/or attempts to refold theforms as they are processed through high-speed printers or the like,have produced additional problems. For example, at high printer speedswhen only a few lines are printed on each card, sudden stops followinghigh-speed longdistance line skipping have resulted in kinking orundesired stiffening of the form during refolding, especially in thecase of wide breakout tabulating card forms having offset scores. Toovercome this problem dummy lines of printing could be inserted toreduce the distance of highspeed skipping; but, obviously, this preventsoptimum operation and throughput.

SUMMARY OF THE INVENTION Applicants have discovered that disadvantagesand problems of the type above described can be. overcome by providing acontinuous card form employing a fold score consisting solely of aseries of uniformly spaced perforations transversely aligned with andpreferably the same size as the perforations along the madial strip.This economically provides a truly straight fold line coincident withthe common center line of all of the transversely aligned perforations.This type of fold score can always be cut from one side of the formconcurrently with the cutting of the perforations inset from the longedges of the break-out card. This fold score also has a memoryfacilitating refolding in the same direction as the initial fold. Byusing this type of fold score and reducing the inherent structuralstrength of the medial strip especially in areas generallylongitudinally aligned with lines of weakness between adjacent cards ofa multiple-card width form or between card and stub portions, kinkingand consequent failure to stack properly during refolding have beeneliminated. Structural strength of the medial strip may be reduced inseveral ways. In the case of either a grain long or grain shortcontinuous card form, cut a slot in preselected areas of the medialstrip adjacent the fold line; and/or in the case of grain long forms,bond the overlying medialstrip-defining edges of the form only attransversely spaced preselected areas (rather than along the entirelength of the medial strip as heretofore).

Other objects and advantages will become apparent from the followingmore detailed description of the invention and from the accompanyingdrawings, wherein:

FIG. 1 is a fragmentary plan view of a grain long continuous card formaccording to one embodiment of the invention;

FIGS. 2 and 3 are fragmentary views, to enlarged scale, of differentportions of the form of FIG. 1;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 1, withthickness exaggerated for clarity;

FIG. 5 is a sectional view taken along line 55 of FIG. 3;

FIG. 6 is a fragmentary plan view comparable to that of FIG. 2 but ofa'prior art continuous card form with a widely used conventional foldscore;

FIGS. 7A and 7B are sectional views to enlarged scale taken along theline 7-7 of FIG. 6 denoting condition of the holding tie respectivelybefore and after folding of the prior art form;

FIGS. 8A, 8B, and 8C are sectional views to enlarged scale taken alongthe line 8-8 of FIG. 6 denoting, respectively, the position of the cardedge of the prior art form before folding, and two positions the cardedge may assume relative to the medial strip edge after folding;

FIG. 9 is a side elevational view of the delivery section of a printer,schematically showing the sequence of positions assumed by a continuousform during refolding in proper manner;

FIG. 10 is a view, like FIG. 9, but showing improper refolding ue totoggle-like stiffening of the form along the score line, such as canoccur when sudden stops follow high-speed long-distance line skips in ahigh-speed printer.

FIGS. 11 and 12 are views, generally like FIG. 3, but showing otherembodiments of the invention as applied 'to grain long continuous cardforms; and

FIGS. 13 and 14 are views, comparable to those in FIGS. 1 and 3,illustrating a grain short continuous card form according to stillanother embodiment of the invention.

DESCRIPTION As illustrated in FIG. 1, the invention is shown embodied ina grain long continuous tabulating card form l-comprising a series ofpairs of side-by-side arranged grain long cards 1 l, 12. Grain means thedirection in which the paper is run through a paper machine during itsmanufacture, there being a greater orientation of fibers in thedirection of travel. Grain long means that the grain runs in the longdirection of the cards 11, 12 (see FIG. 1); whereas grain short meansthe grain runs in the shortdirection (see FIG. 13). The cards 11, 12 ofeach pair are detachably connected along their adjacent short ends bylines of weakness defined by cuts, such as 13, 14, extendinglongitudinally in laterally spaced and longitudinally staggered relationto proslits 21, 22, respectively, that are thus laterally offsetslightly from the interior edge 23 of the central part of each'cutout-18; the spaces between slits 2l, 22 thus serve as holding ties 24. Asillustrated, cards ll, 12 have three rounded corners 25, and a singleangled corner cut 26 attheir upper left corners. Marginal strips 16, 17.have uniformly spaced pinfeed holes 27 for receiving the forms tractorpins (not shown) that advance the form through a high-speed printer.

The cardsll, 12 of each pair are detachably connected to the cards of anadjacent pair by medial strips 28. As best shown in FIGS. 2-5, thesestrips'28 are defined by upper and lower overlapping edge portions U andL, respectively, which have facing stripes S of heatsetting adhesive bywhich said portions are adhered to each other to create the continuouscard form. Each card 11, 12 is detachably connected to the adjacentmedial strips 28 by a plurality of groups of transversely alignedperforations 29 identical in size and number and uniformly spaced fromeach other; and a series of slits 30 that cut tangentially into andextend tangentially from the outermost perforation of one group into theoutermost perforation of the adjacent group. The spaces between theperforations of each group thus constitute holding ties 31 that hold theform together until it is burst to break out the individual cards 11, 12from the medial strips 28 and marginal strips 16, 17. The form as thusfar described is substantially identical with that of the prior art.

According to the invention, and as shown in FIGS. 1 to 3, the improvedform 10 has a series of uniformly spaced additional perforations 32extending across the marginal strips 16, 17 in precise transversealignment with the perforations 29 and cut concurrently therewith in asingle operation. The fold score perforations 32 preferably are of thesame diameter as perforations 29. The slits 30 that extend into themarginal strip cut tangentially into the innermost .of the perforations32.

These perforations 32, 29 cooperate to provide a fold line (see FIG. 2)that is perfectly straight and coincident with the center line of allthe transversely aligned perforations 32, 29.

Form 10 also has an elongated slot 34 (FIG. 3) cut from the medial strip28 immediately adjacent the card edge between two sets of adjacentperforations 29. This slot preferably extends across and to each side ofan imaginary projection of the line of weakness defined by the cuts l3,l4 and ties 15; and the slot (see FIG. 5) has been found adequate forits intended functions even though formed by removal of cardstock onlyfrom the lower portion L of the medial strip 28. This slot is providedto significantly reduce the structural strength of the medial strip 28,thereby positively to insure that the three-up continuous card form 10will assume the proper sequence of positions, illustrated as a, b, c, din FIG. 9, for proper zigzag refolding on a stack 41 after leaving thetractor feed rolls 42, 43 in the delivery section of a printer 44. Notethat fold line 33 moves progressively downward and outward to one sidesuccessively to the positions a, b, c, and d, while the next fold line133 moves into proper position for progressive downward and outwardmovement to the opposite side of the stack.

In FIG. 6 there is illustrated a grain long continuous card form 10 ofthe conventional prior art type disclosed in U. S. Pat. No. 2,700,556.Instead of perforations like 32, form 10 employs short cuts 100transversely aligned with and cut concurrently with slits 30 that extendtangentially from perforations 29. These cuts 100 constitute a foldscore which is made at every medial strip irrespective of where the formis to be initially folded and later refolded. As heretofore noted, if aform 10' is to be stacked three-up," i.e., with three pairs of cards 11,12 between folds, the beveledknife blades cut alternately from first thefront, then the back of the form 10 at each successive medial strip; buteven if this is done, the form will fold along an irregular line 101.This irregular fold line 101 coincides with the center line of thealigned perforations 29 until it reaches the marginal strips 16', 17';then it shifts slightly to coincide with the line of short cuts 100.Also, in the form 10 of the prior art, the superposed stripes S of heatsealing adhesive are adhered along the entire length of the medial strip28; and, except for the slits 30 and perforations 29' that define theline of separation between the cards and medial strip, the medial stripremains intact and structurally strong. As a result, certain problemshave been encountered which are inexpensively and successfully overcomein the improved continuous card form 10.

It has been found that when a form like the threeup" prior artcontinuous card form 10' shown in FIG. 6 is processed through ahigh-speed, e.g., 2,000 lines per minute, printer, there are conditionsunder which I improper refolding and misstacking will occur; e.g.,

when sudden stops follow high-speed long-distance line skips. Theseconditions frequently cause the fold line 101 to swing past center;i.e., as viewed in FIG. 10, to swing initially left of center to theposition shown in a, rather than right of center. This over-centertoggle-like stiffening or kinking causes fold line 101 to become lockedpast center. As a result, form 10' starts to fold along the closestdownstream card edge score W and irreversibly initiates a misstackingsequence, wherein fold line 101 and card edge score W move downward andrightward successively to the positions shown in a, b, 0. Meanwhile,card edge score V upstream of the locked-over-center fold line 101buckles and folds as shown in b and c. It is now impossible for the nextfold line 101' to reach the left edge of stack 41', even if the formdoes eventually buckle or fold along line 101. From this instant on, thedisarray will become progressively worse, requiring shutdown of theprinter to alleviate thestacking jam.

The reason why the over-center locking action occurred along fold line101 can best be understood by reference to FIGS. 6, 7, and 8. In formthe cuts 100 in combination with the perforations 29 provide theirregular fold line 101. Before initial folding of the form along line101, the holding ties 102 between perforations 29' and the slits assumethe positions shown in FIGS. 7A and 8A, respectively. Folding causes theholding ties 102 to-shrink to the extent indicated at 103 due tostresses imposed on the card fibers. During subsequent refolding, if thecard edge 104 along slit 30' swings so as to overlap the lower portion Lof medial strip 28, as illustrated in FIG. 8B, form 10' will fold alongline 101 and stack properly. However, if edge 104 butts against medialstrip 28, as illustrated in FIG. 8C, the overcenter toggle-like lockingaction shown in FIG. 10 will occur and prevent refolding.

It has been determined by actual test that this overcenter lockingaction isprevented by significantly reducing the strength of the medialstrip at least at one critical area along its length.

As illustrated in FIGS. 1 to 5, elongated slot 34 is a cut about 0.030inch wide and extending from one group of perforations 29 to theadjacent group. Where, as illustrated, the portions U, L of the medialstrip 28 do not completely overlap, it is sufficient that the slot 34 becut through only one of the portions, e.g., lower portion L, of themedial strip, which desirably minimizes the cutting force required. Byhaving one edge of slot 34 aligned with slit 30, the slot can be cut atthe same time as and with the same tool that cuts the slit. This slotpermits the medial strip to collapse and deflect toward the middle ofthe slot and thus destroy the beam effect" that enabled the fold line tolock over center.

In the double-width form 10 illustrated, the critical I area was foundto be adjacent the center line of the web, at and to each side of theline of weakness separating the cards 11, 12. In forms of otherconstruction, the critical areas generally are aligned with longitudinallines of weakness because the form has the greatest tenremove theover-center locking possibility from each section by a series of slotsacross the entire width of the form; e.g., from each group ofperforations 29 to the adjacent group, essentially replacing all slits30 with slots 34.

The ease of stacking is further improved by reducing the amount ofmedial strip shrinkage. This shrinkage occurs when the cards are heatedalong the medial strips 2 to effect bonding of the superposed stripes Sof heat sealing adhesive. The heat causes the medial strip to shrink andpermanently become shorter in length than the body of the card 11 or 12to which it is attached by the holding ties 31. This, in turn, places agreater stress on the holding ties, increases the bending of the cardform in the transverse direction and creates a tendency for the form tofold at a point such as W or V (FIG. 10) which is downstream or upstreamof the fold score line 101.

It has been found by actual test that medial strip shrinkage can besubstantially eliminated by heating only preselected areas of the medialstrip 28 so that the superposed strips S of heat sealing adhesive willbond only at said areas. As illustrated in FIG. 3, these areaspreferably are longitudinally aligned with cuts 13, 14 as denoted at 150and aligned with the opposed sets of perforations 29 as denoted at 151.For ease of manufacture, it is preferable that the adhesive be appliedas stripes S extending the full length of the medial strips but that itbe bonded only at the preselected areas 150, 151; this may beaccomplished readily be recessing the otherwise solid heater bar (notshown) at those locations where bonding is not desired. Of course, ifpreferred, the adhesive could be selectively applied only to thepreselected areas. Stripes S may also be bonded at 153.

Other embodiments of the invention are illustrated in FIGS. 11 to 14.

FIG. ll shows a grain long continuous card form without rounded cornersor slash cuts. A slot 134 in the lower portion of the medial strip 128has one edge aligned with slits 130 and extending longitudinally fromthe perforations 129 transversely of the line of the cuts 113, 114.

In FIG. 12 grain long form 110 has a series of slots 134' that aresubstantially larger than slots 134 and are cut through both plies ofthe medial strip 128'. Both (rather than only one) of the edges of theslots extend tangentially between adjacent sets of perforations 129; andthese slots are provided across the form except at the marginal strips(not shown) so as to leave unslotted essentially only the areas 151extending longitudinally between opposed sets of perforations 129'.

In the cards 110, 110, fold score perforations (not shown, but similarto perforations 32 of FIGS. 1-5) are provided in the marginal strips inprecise transverse alignment with perforations 129, 129' to provide thestraight fold line 133, 133, respectively.

FIGS. 13 and 14 illustrate a grain short continuous card form 210 inwhich the medial strip 228 is constituted, in conventional manner, byonly a single continuous ply or web of cardstock appropriately providedwith slits 230 and sets of perforations 229. However, according to theinvention, perforations 232 are provided in the marginal strips 216, 217precisely trans-.

versely aligned with perforations 229 at selected longitudinal pointswhere folding is desired. One elongated slot 234 (or if desired, aplurality of slots 234) is cutout from the medial strip 228. Since themedial strip 228 is merely a single ply, there is, of course, no heatsealing.

The fold score perforations, e.g., 32, 232, may be aligned with eitherthe leading or trailing long edge of the medial strip. However, it hasbeen found preferable to provide the fold score perforations along thatedge of the medial strip which is the leading edge when the 7 forms areinitially folded. This may or may not be the leading edge of the cardduring subsequent refolding, as during a run through a printer; however,during each refolding, it is also preferable that the fold scoreperforations be at the leading edge of the medial strip.

It is to be understood that the slots 34, 134, 134' or 234,- and/or theunadhered areas between 150, 151, and/or other types of structuralweakening may be employed with each medial strip 28, 128, 128' or 228,rather than with only those adjacent a fold line 33, 133,

133 or 233., as no harm is done by weakening each medial strip.

With the improved forms herein disclosed, fold score perforations, e.g.,32, are provided in the marginal strips only where folding (orrefolding) is desired; thus, for a three-up form, where folding isdesired only after each series of three cards, fold perforations will beprovided only at every third medial strip. Since the form with punchedhole perforations will fold with equal facility from either side, allfold perforations may be made from the same side, facilitatingmanufacture; also, they maybe made at any desired interval according towhether-one-up, two-up, three-up, four-up or sixupforms are preferred.

Moreover, thefold score perforations provide a fold I score line 33,133, 133 or 233 of more uniform strength than that obtained with thecuts 100 of FIG. 6. They also provide holding ties, e.g., 53 or 253,between the fold score perforations that cause negligible breakingand/or weakening of the cardstock immediately adjacent saidperforations. In contrast, the slit cuts 100 often partially broke theholding ties because of the bevel of the cutting blade and/or dullnessof its cutting edge. The shearing-type cutting tools that provide thefold score perforations last longer than the tools used to make the slitcuts 100; this facilitates initial folding at the time of manufacture,and assures greater throughput and reduced maintenance time.

While the invention has been particularly shown and describedwithreference to preferred embodiments thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formand details may be made therein without departing from the spirit andscope of the invention.

What is claimed is:

1. A continuous card form of the type wherein a series of machineprocessable breakout tabulating cards are detachably connected tomarginal strips containing uniformly spaced pin-feed holes and alsodetachably connected to narrow medial strip portions extending acrossthe form and separating successive cards, and wherein cuts and tiesdefine respective lines of separation of each marginal strip from thecards, and a plurality of groups of perforations and of interveningslits that extend tangentially from the outermost perforations of eachgroup to those of the next group constitute respective other lines ofseparation of each medial strip portion from the cards extending betweeneach of said marginal strips to the other, said other lines ofseparation being arranged in pairs extending across the form, each ofsaid pairs defining one of said medial strip portions, characterized inthat at each spaced preselected location along the form where the formis to be folded, each marginal strip is provided with a fold scoreconsisting solely of respective sets of additional perforationstransversely aligned with a corresponding set of the first-mentionedperforations and formed simultaneously therewith, and

two additional slits are provided which are cut simultaneously with theintervening slits and extend tangentially from the respective outermostperforation of each of such corresponding sets into the respectivemarginal strips tangentially to the innermost additional perforationaligned with such corresponding set, whereby the form at each suchlocation will fold along a continuous straight fold line coincident withthe center line of all the transversely aligned perforations at saidlocation, and will initially fold with equal facility in eitherdirection but, once folded, have a memory facilitating refolding in thesame direction, and the form comprises a series of at least two partsdetachably connected to each other by lines of weakness along theirrespective short edges between the marginal strips as well as detachablyconnected to common medial strips, and each medial strip that isadjacent to a fold score is conditioned to reduce its structuralstrength, at least at and slightly to either side of each point where itis intersected by an imaginary longitudinal projection of such lines ofweakness, thereby to preclude toggle-like stiffening or kinking of theform during refolding. 2. A continuous card form according to claim 1,further characterized in that said additional perforations are of thesame size as the first-mentioned perforations and extend acrosssubstantially the entire width of the marginal strips.

3. A continuous card form according to claim 1, further characterized inthat each medial strip which is adjacent a fold score has at least onerectangular slot therein having its long dimension extending parallel tothe fold line to reduce its structural strength, thereby to precludetoggle-like stiffening or kinking of the form during refolding. 4. Acontinuous card form according to claim 1, further characterized in thatsaid sets of additional perforations are transversely aligned with theperforations defining the leading long edge of the medial strip duringthe initial zigzag folding of the form. 5. A continuous card formaccording to claim 1, wherein said medial strip is in part defined byover-lapping adhered long edge portions of adjacent grain long cards,and v each medial strip which is adjacent a fold score has a pluralityof preselected areas spaced along its length where the overlappingmedial-stripconstituting portions are unadhered, thereby to reduce thestructural strength of such medial strip along the fold score and tominimize strip shrinkage to preclude toggle-like stiffening or kinkingof the form during refolding.

6. A continuous card form according to claim 1,

wherein said medial strip is in part defined by over-lapping long edgeportions of adjacent grain long cards, and

at least one slot is provided having at least one of its long edgesprecisely aligned with said slits.

7. A grain long continuous card form according to claim 6, wherein eachslot is relatively long and narrow and cuts through only a single plyportion of the medial strip immediately adjacent said overlapping longedge portions. 8. A continuous card form according to claim 6, whereinthe overlapping edge portions of the medial strip are adhered only attransversely spaced areas including those between longitudinally alignedsets of perforations in order to reduce medial strip shrinkage andfacilitate folding and refolding. 9. A continuous card form according toclaim 1, further characterized in that the form is a grain shortcontinuous card form having a single ply medial strip, and

said sets of additional perforations are transversely aligned with theperforations defining the leading long edge of the medial strip duringthe initial zigzag folding of the form, and

at least one slot is provided extending transversely of the form anddisposed between the opposing sets of slits defining the leading andtrailing edges of the medial strip.

10. A continuous form according to claim 1 characterized in that thesaid cards are grain long" and said medial strips extend parallel to thegrain and are defined by overlapping portions between the upper andlower ends of the respective said at least two parts.

1. A continuous card form of the type wherein a series of machineprocessable breakout tabulating cards are detachably connected tomarginal strips containing uniformly spaced pin-feed holes and alsodetachably connected to narrow medial strip portions extending acrossthe form and separating successive cards, and wherein cuts and tiesdefine respective lines of separation of each marginal strip from thecards, and a plurality of groups of perforations and of interveningslits that extend tangentially from the outermost perforations of eachgroup to those of the next group constitute respective other lines ofseparation of each medial strip portion from the cards extending betweeneach of said marginal strips to the other, said other lines ofseparation being arranged in pairs extending across the form, each ofsaid pairs defining one of said medial strip portions, characterized inthat at each spaced preselected location along the form where the formis to be folded, each marginal strip is provided with a fold scoreconsisting solely of respective sets of additional perforationstransversely aligned with a corresponding set of the first-mentionedperforations and formed simultaneously therewith, and two additionalslits are provided which are cut simultaneously with the interveningslits and extend tangentially from the respective outermost perforationof each of such corresponding sets into the respective marginal stripstangentially to the innermost additional perforation aligned with suchcorresponding set, whereby the form at each such location will foldalong a continuous straight fold line coincident with the center line ofall the transversely aligned perforations at said location, and willinitially fold with equal facility in either direction but, once folded,have a memory facilitating refolding in the same direction, and the formcomprises a series of at least two parts detachably connected to eachother by lines of weakness along their respective short edges betweenthe marginal strips as well as detachably connected to common medialstrips, and each medial strip that is adjacent to a fold score isconditioned to reduce its structural strength, at least at and slightlyto either side of each point where it is intersected by an imaginarylongitudinal projection of such lines of weakness, thereby to precludetoggle-like stiffening or kinking of the form during refolding.
 2. Acontinuous card form according to claim 1, further characterized in thatsaid additional perforations are of the same size as the first-mentionedperforations and extend across substantially the entire width of themarginal strips.
 3. A continuous card form according to claim 1, furthercharacterized in that each medial strip which is adjacent a fold scorehas at least one rectangular slot therein having its long dimensionextending parallel to the fold line to reduce its structural strength,thereby to preclude toggle-like stiffening or kinking of the form duringrefolding.
 4. A continuous card form according to claim 1, furthercharacterized in that saiD sets of additional perforations aretransversely aligned with the perforations defining the leading longedge of the medial strip during the initial zigzag folding of the form.5. A continuous card form according to claim 1, wherein said medialstrip is in part defined by over-lapping adhered long edge portions ofadjacent grain long cards, and each medial strip which is adjacent afold score has a plurality of preselected areas spaced along its lengthwhere the overlapping medial-strip-constituting portions are unadhered,thereby to reduce the structural strength of such medial strip along thefold score and to minimize strip shrinkage to preclude toggle-likestiffening or kinking of the form during refolding.
 6. A continuous cardform according to claim 1, wherein said medial strip is in part definedby over-lapping long edge portions of adjacent grain long cards, and atleast one slot is provided having at least one of its long edgesprecisely aligned with said slits.
 7. A grain long continuous card formaccording to claim 6, wherein each slot is relatively long and narrowand cuts through only a single ply portion of the medial stripimmediately adjacent said overlapping long edge portions.
 8. Acontinuous card form according to claim 6, wherein the overlapping edgeportions of the medial strip are adhered only at transversely spacedareas including those between longitudinally aligned sets ofperforations in order to reduce medial strip shrinkage and facilitatefolding and refolding.
 9. A continuous card form according to claim 1,further characterized in that the form is a grain short continuous cardform having a single ply medial strip, and said sets of additionalperforations are transversely aligned with the perforations defining theleading long edge of the medial strip during the initial zigzag foldingof the form, and at least one slot is provided extending transversely ofthe form and disposed between the opposing sets of slits defining theleading and trailing edges of the medial strip.
 10. A continuous formaccording to claim 1 characterized in that the said cards are ''''grainlong'''' and said medial strips extend parallel to the grain and aredefined by overlapping portions between the upper and lower ends of therespective said at least two parts.